Square sink



FIG. 1 is a top perspective view of a square sink embodying my new design;

FIG. 2 is a side plan view thereof, the front, back, left and right sides having the same image;

FIG. 3 is a top plan view thereof; and,

FIG. 4 is a bottom plan view thereof.

The broken lines shown in the drawings represent a hole in the sink and form no part of the claimed design. 

CLAIM The ornamental design for a square sink, as shown and described. 